1. Field of the Invention
This invention relates to a plantable wall block assembly comprising a plurality of modular wall blocks with connectors therefor, and retaining walls constructed therewith including geogrid reinforcing sheet material, where necessary.
2. Description of the Prior Art
Modular wall block assemblies for construction of retaining walls are frequently used for architectural and site development applications. Since the wall facing must sometimes withstand very high pressures exerted by backfill soils, reinforcement and stabilization of the soil backfill is commonly provided by grid-like sheet materials, known as geogrids, that are placed in layers in the soil fill behind the wall face to interlock with the fill and create a stable reinforced soil mass. Connection of the reinforcing materials to the elements forming the wall holds the wall and elements in place and resists soil backfill pressures.
Superimposed courses of wall blocks are staggered laterally to facilitate interlocking superior wall blocks with those they overly. Many modular wall block assemblies are provided with means to adjust the stepped-back relationship of superior courses to enable the walls to be constructed with the front faces of the wall blocks vertically aligned or set back to angle the relationship of the wall to the foundation.
Often times, it is desired to provide plant-receiving cavities in the forward portions of modular wall blocks for aesthetic purposes and/or to minimize erosion of the soil fill material. One example of a plantable wall block is seen in Dawson U.S. Pat. No. 5,601,384 wherein the design of the block enables limited selectivity in set-back with the principal plant-receiving cavities being provided by the laterally staggered nature of the blocks in superimposed courses.
An earlier version of a retaining wall formed from a plantable wall block is seen in Giardini U.S. Pat. No. 4,671,706 wherein the blocks are stepped-back by the selective engagement of a depending flange on the front wall of superior blocks in one of a plurality of spaced notches in the side walls of inferior blocks. Blocks of this nature are difficult to store because the flanges are easily broken, limiting the usefulness of such a system.
The plantable wall block assembly seen in Jansson U.S. Pat. No. 5,564,865 relies on an elongated tensioning member passing through blocks in the various courses to tie the wall together, an obvious tedious and difficult construction. While Jansson does provide for means to secure a geogrid to the retaining wall, the connection relies solely on the weight of superimposed wall blocks, a construction particularly subject to damage during a seismic event, such as an earthquake, or the like. Miller et al U.S. Pat. Nos. 5,564,525 and 5,595,460 show comb-like connectors adapted to mechanically interlock geogrid or the like to selected modular wall block to preclude such problems.